r8169: enable 64-bit DMA by default for PCI Express devices (v2)
Currently use of 64-bit DMA is disabled in r8169 unless the user passes the use_dac module option. This is reasonable for conventional PCI devices where broken chipsets may not handle dual-address-cycle transfers properly for 32-bit slots and so this may not be safe. However, PCI Express should not have this problem and not using 64-bit DMA results in DMA transfers needlessly using the IOMMU or SWIOTLB. Set the use_dac module parameter to a new default value of -1 which results in 64-bit DMA being enabled by default for PCI Express devices only. Signed-off-by: Robert Hancock <hancockrwd@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -187,7 +187,7 @@ static DEFINE_PCI_DEVICE_TABLE(rtl8169_pci_tbl) = {
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MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);
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static int rx_copybreak = 200;
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static int use_dac;
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static int use_dac = -1;
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static struct {
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u32 msg_enable;
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} debug = { -1 };
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@ -511,7 +511,8 @@ MODULE_DESCRIPTION("RealTek RTL-8169 Gigabit Ethernet driver");
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module_param(rx_copybreak, int, 0);
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MODULE_PARM_DESC(rx_copybreak, "Copy breakpoint for copy-only-tiny-frames");
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module_param(use_dac, int, 0);
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MODULE_PARM_DESC(use_dac, "Enable PCI DAC. Unsafe on 32 bit PCI slot.");
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MODULE_PARM_DESC(use_dac, "Enable PCI DAC. -1 defaults on for PCI Express only."
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" Unsafe on 32 bit PCI slot.");
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module_param_named(debug, debug.msg_enable, int, 0);
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MODULE_PARM_DESC(debug, "Debug verbosity level (0=none, ..., 16=all)");
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MODULE_LICENSE("GPL");
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@ -2973,6 +2974,7 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
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void __iomem *ioaddr;
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unsigned int i;
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int rc;
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int this_use_dac = use_dac;
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if (netif_msg_drv(&debug)) {
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printk(KERN_INFO "%s Gigabit Ethernet driver %s loaded\n",
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@ -3038,8 +3040,17 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
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tp->cp_cmd = PCIMulRW | RxChkSum;
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tp->pcie_cap = pci_find_capability(pdev, PCI_CAP_ID_EXP);
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if (!tp->pcie_cap)
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netif_info(tp, probe, dev, "no PCI Express capability\n");
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if (this_use_dac < 0)
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this_use_dac = tp->pcie_cap != 0;
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if ((sizeof(dma_addr_t) > 4) &&
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!pci_set_dma_mask(pdev, DMA_BIT_MASK(64)) && use_dac) {
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this_use_dac &&
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!pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
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netif_info(tp, probe, dev, "using 64-bit DMA\n");
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tp->cp_cmd |= PCIDAC;
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dev->features |= NETIF_F_HIGHDMA;
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} else {
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@ -3058,10 +3069,6 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
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goto err_out_free_res_4;
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}
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tp->pcie_cap = pci_find_capability(pdev, PCI_CAP_ID_EXP);
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if (!tp->pcie_cap)
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netif_info(tp, probe, dev, "no PCI Express capability\n");
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RTL_W16(IntrMask, 0x0000);
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/* Soft reset the chip. */
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